android client parse multipart form data to non ascii

Question

can you explain why android client parse multiparform data to non ascii chat. while file upload working good using postman here is my app.js code

var multipart = require('connect-multiparty');
var apiRoutes = require('./routes/apiRoutes');
app.set('views', path.join(__dirname, 'views'));
app.use(logger('dev'));
app.use(bodyParser.json({limit: '50mb'}));
app.use(bodyParser.urlencoded([{extended: false},{ uploadDir:path.join(__dirname, 'uploads') }, {parameterLimit:100000}, {limit: '50mb'}]));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use(express.static(path.join(__dirname, 'uploads')));
app.use(multipart());
app.use(apiRoutes);

and apiRoutes point my upload function contain simple print req param.using postman it working good

console.log("mediaChat called", req.body, req.files);

response

mediaChat called { apiKey: '123' } { media: 
   { fieldName: 'media',
     originalFilename: 'default.png',
     path: '/tmp/KFnwsKGp-f4woTaBH6aPR-qa.png',
     headers: 
      { 'content-disposition': 'form-data; name="media"; filename="default.png"',
        'content-type': 'image/png' },
     size: 716,
     name: 'default.png',
     type: 'image/png' } }

here is my android client code (Note this code working file with php $_FILE but not working with express)

com.info.acruss.wave;

import android.os.AsyncTask;
import android.util.Log;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Created by Naitik on 9/20/2016.
 */
public class UploadImage extends AsyncTask<Void, Void, String> {
    String CallingURL;
    URL url;
    OnTaskCompleted myListener;
    private static final String TAG = "UploadImage";
    int timeoutMilli = 60000;
    String sourceFileUri;
    String ApiKey,Type;

    public UploadImage(String sourceFileUri, String URL,String apiKey, String type,
                       OnTaskCompleted listener) {
        Log.e("Uploading", "API:" + URL);
        this.sourceFileUri = sourceFileUri;
        this.CallingURL = URL;
        this.myListener = listener;
        this.ApiKey=apiKey;
        this.Type=type;
        try {
            url = new URL(CallingURL);
            Log.e(TAG, "Url : " + CallingURL);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected String doInBackground(Void... params) {
        String fileName = sourceFileUri;
        HttpURLConnection conn = null;
        DataOutputStream dos = null;
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 10 * 1024 * 1024;
        File sourceFile = new File(sourceFileUri);
        if (!sourceFile.isFile()) {
            Log.e("UploadImage", "Source File Does not exist";
            return null;
        }
        String serverResponseMessage = "";
        try {

            // open a URL connection to the Servlet
            FileInputStream fileInputStream = new FileInputStream(sourceFile);
            URL url = new URL(CallingURL);
            // Open a HTTP  connection to  the URL
            conn = (HttpURLConnection) url.openConnection();
            conn.setDoInput(true); // Allow Inputs
            conn.setDoOutput(true); // Allow Outputs
            conn.setUseCaches(false); // Don't use a Cached Copy
            conn.setRequestMethod("POST";
            conn.setReadTimeout(timeoutMilli);
            conn.setConnectTimeout(timeoutMilli);
            conn.setRequestProperty("Connection", "Keep-Alive";
            conn.setRequestProperty("ENCTYPE", "multipart/form-data";
            conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
            conn.setRequestProperty("media", fileName);
            conn.setRequestProperty("apiKey",ApiKey);
            conn.setRequestProperty("media_type",Type);
            conn.setRequestProperty("media", fileName);

            dos = new DataOutputStream(conn.getOutputStream());
            dos.writeBytes(twoHyphens + boundary + lineEnd);
            dos.writeBytes("Content-Disposition: form-data; name='media';filename='" + fileName + "'" + lineEnd);
               dos.writeBytes(lineEnd);
            // create a buffer of  maximum size
            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            buffer = new byte[bufferSize];

            // read file and write it into form...
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);

            while (bytesRead > 0) {

                dos.write(buffer, 0, bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);

            }

            // send multipart form data necesssary after file data...
            dos.writeBytes(lineEnd);
            dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

            // Responses from the server (code and message)
            int serverResponseCode = conn.getResponseCode();

            BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line = "";
            StringBuilder responseOutput = new StringBuilder();
            while ((line = br.readLine()) != null) {
                responseOutput.append(line);
            }
            br.close();
            serverResponseMessage = responseOutput.toString();//output.toString();

            Log.e("uploadFile", "HTTP Response is : " + serverResponseMessage);
            if (serverResponseCode == 200) {
                //status code 200
                //status ok
            }
            //close the streams //
            fileInputStream.close();
            dos.flush();
            dos.close();

        } catch (MalformedURLException ex) {
            ex.printStackTrace();
            Log.e("Upload file to server", "error: " + ex.getMessage(), ex);
        } catch (Exception e) {
            Log.e("Upload file to server", "error: " + e.getMessage(), e);
            e.printStackTrace();
        }
        return serverResponseMessage;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        Log.e("Result", "" + result);
        if (myListener != null)
            if (result != null) {
                myListener.onFileUploadComplete(result);
            } else {
                myListener.onFileUploadComplete("";
            }
    }

    public interface OnTaskCompleted {
        void onFileUploadComplete(String result);
    }
}

using android this show wired response as below

mediaChat called { null: '����\u0000\u0010JFIF\u0000\u0001\u0001\u0000\u0000\u0001\u0000\u0001\u0000\u0000��\u0000C\u0000\u0010\u000b\f\u000e\f\n\u0010\u000e\r\u000e\u0012\u0011\u0010\u0013\u0018(\u001a\u0018\u0016\u0016\u00181#%\u001d(:3=Mqypdx\\egc��\u0000C\u0001\u0011\u0012\u0012\u0018\u0015\u0018/\u001a\u001a/cB8Bccccccccccc....
�\u001f.[���_�\u0014)M���XIjX��7�`=�/�8`��ïDʚ\u0018�D���#�V#q~m�q10L�' }

i also tried multer and other multipart handler but noting works. please help me to out from this hell

Answer 1

It seems the server response is encoded as UTF-8. To properly decode and read you could try

BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));

Specifying the encoding part to the InputStreamReader will decode and read the stream using specified encoding scheme, which in this case is UTF-8. Check the javadocs for details.